Abstract In the Underwater Wireless Sensor Networks (UWSN) provide a solution for several aquatic and oceanographic applications. All these UWSN applications are need to be aware of the nodes positioning. In some insecure environment, the misleading data can be transmitted to the sonobuoys or monitoring systems in the network. This may disrupt the functions of the nodes. Thus, the secured localization algorithms are designed to resistant against attack and try to achieve the localization correctly. This paper shows that modified secure localization algorithm based Gradient Descent Algorithm (GDA) to remove the misleading information in the networks. This modified algorithms the normal nodes are cooperate with each other to reduce the localization error and to improve the pruning percentage.